Clean water used by personnel performing labor at oil and gas well sites is commonly delivered and stored in water tanks at the well site. Water is also needed at well sites during drilling operations for drilling fluid, also called drilling mud. The purchase, delivery, and storage of water at well sites can be a significant part of overhead associated with drilling operations.
Many tasks and operations at oil and gas well sites, including drilling operations, require human labor. The presence of well site personnel and their water needs may vary. Most if not all personnel at well sites require the use of restrooms. Personnel residing at well sites over multiple days require running water for drinking, cooking, cleaning dishes, and washing clothes. Consequently, human activity at oil and gas well sites commonly results in at least two types of waste water, including blackwater, and greywater.
Blackwater results from restrooms and is wastewater containing feces, urine and flushwater from flush toilets or toilet paper. Greywater or sullage is generally wastewater generated in households or office buildings from streams without fecal contamination, i.e. all streams except for the wastewater from toilets. Greywater may include the wastewater resulting from cleaning dishes and washing clothes. Blackwater and greywater are to be distinguished from “produced water,” which term is used in the oil industry to describe water that is produced as a byproduct along with the oil and gas.
Generally, blackwater and greywater resulting from human activity cannot simply be disposed of at an oil or gas well site; rather, industry practice has been to collect the wastewater in holding tanks and then transport it to remote locations for treatment. Often municipal water treatment facilities are contracted to receive and treat blackwater and greywater. The cost for wastewater transport services and to compensate municipal wastewater treatment facilities can significantly increase overhead for well site operations.
There are a number of challenges with collecting and treating blackwater and greywater. Treatment of such wastewater has often had to rely on municipal water treatment facilities or other more permanent water treatment systems. Such facilities may be permanently located at great distances from remote well sites. Such water treatment facilities are generally not built specifically for specific well sites or groups of well sites because of the extensive resources and costs to build them. Likewise, the tentative viability of well sites and scarcity of well sites in a given group to be served make it infeasible to build permanent water treatment facilities for specific well sites or groups of well sites. Once a water treatment facility is built, it is usually fixed to a location and cannot be transported to new sites when needed.
Also, greywater from certain greywater sources at well sites contains substantial amounts of diesel, oil, grease, cuttings, and or drilling mud. Some of these contaminants, such as diesel, kill or otherwise inhibit growth of bacteria and other microorganisms useful for the treatment of waste water.